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A while back there was a thread that addressed the differences in gas brands and that SUNOCO seemed to be best for our engines. Well, I've used SUNOCO for years because there is a station near home --and they've always kept their prices decent.

Now I've really noticed a difference. In my last three fillups I used AMOCO "Silver" the first two. On the last I returned to SUNOCO 89 octane. It was hard to believe that I went about 56 miles further on the SUNOCO! And I always fill up at the 1/2 mark. That may invalidate a specific ultra accurate measuring, but it does seem to support the SUNOCO benefit for Subarus.

Is there any reason for this drastic difference? Are the additives, etc. used by the different gas companies *THAT* different?

Well, to get some really meaningful data, you'd have to fill up at the Sunoco station maybe 5 or 6 times using the same pump, calculating MPG each time and getting an average. Then repeat this for the Amoco. Unless the gas is really bad at that Amoco you mention, there should be no significant difference.

I haven't noticed any meaningful difference in gas consumption on my 99 OBS whether I use Mobil (the "good stuff") or Merit (cheapo Long Island gas ) I switched to Merit a few months ago and have been regularly getting 25-27 mpg with my mostly highway driving.

[This message has been edited by Impresario (edited September 13, 2000).]

woah...maybe i should go back to stock, getting around 150 miles per TANK isn't too fun..especially on 100 octane but the motor loves it, and it smeeeellllssss nice too and i did find that on shell the car ran better than amoco (well that was stock motor...now...all i run is either 93 from shell with NOS octnae boost or straight up 100 octane race fuel)

edit: That 150 is without ANY hard driving and keeping the revs WAAY down, driving hard i get about 8-13 mpg...if i am lucky 13 if not...woah :9 but i am going FI soon too...so glurp glurp glurp there goes more MPG

oh...and what is the best octane booster in your opionion...NOS "the blue bottle" street or race formula (it depends on what i will be doing on that tank) or the less expensive stuff in the red bottle with the horsie on it?

[This message has been edited by 98mpreziveRS (edited September 13, 2000).]

I've done extensive testing for the past two years and have charted every single fillup I've ever done including brands. Go to http://www.trunkmonkey.com/ and click on Team, then Maintenance Log for me. The brands aren't listed on the page (yet, I'm lazy, but the data is in the database) but I did three months on Mobil, three months on Sunoco, etc., all filling up at the same pumps at the same stations.

Sunoco has gotten me the farthest each time. My record so far is 419 miles on one fillup with Sunoco 94 with my MY98 Impreza 2.2L Wagon. Yeehaw!

I've noticeed 50 mor miles to the tank with both Shell and Sunoco. Mobil, Exxon, Merit, and Citgo have been the worst. Texaco splits the differnece and Amoco splits it between Texaco and Shell and Sunoco

Thank you. I agree that I would have to set up a much more controlled watch on my fuel consumption to draw any definite conclusons, but there seems to be a good bit of evidence to support the view that there IS a wider variation among gas brands than I would have thought. My driving does not vary very much: its pre-rush hour highway travel to and from work, a couple of local errands in the evenings and ferrying my son to soccer games on Saturdays and Sundays (his team travels to games in Northern Virginia and Central Maryland --again, mostly hightway cruising in 5th at about 65 mph. Boy, this looks boring and consistent...maybe I'd better listen to some more Jimmy Buffet!!!!

well the answer is my motor looks lightly modded...but is infact kinda "heavily" modded afer all...i jacked up the compression ratio, did some minor milling, etc., bored out stock injectors, will soon be getting some cams either from cobb or have some custom ground, header purchase and installation soon, then eventually a whole new motor with a turbo and then build up this one as an NA beast!

A majority of my driving is at a set speed like on a highway or on a set routine like on my way to work, these mileages are very consistent when using the same brand of gas. The change drasticlaly when I change fuel brands.

All comparisons were made with 87 octane in the Subaru and the comparisons were done using 93 octane in my Porsche with the same results, better mileage on Shell and Sunoco.